Dynamo-electric machine.



A. L. CUSHMAN.

DYNAMO ELBGTRIG MACHINE. APPLICATION FILED FBBJ15, 1908.

932,537, Patented Aug.31, 1909.

Z haaasea- Izaak 72257. W1 Ma y ,flie c022 Cask/22am UNITED STATESPATENT OFFICE.

ABE LINCOLN CUSHMAN, 0F CONCORD, NEW HAMPSHIRE, ASSIGNOR OF ONE-HALF TOBENJAMIN A. KIMBALL, 01 CONCORD, NEW HAMPSHIRE.

Specification of Letters Patent.

Patented Aug. 31, 1909.

Application filed February 15, 1908. Serial No. 415,998.

To all whom it may concern:

to it known that I, Am: LINCOLN CUSH- MAN, a. citizen of the UnitedStates, and resident of Concord, in the county of Merrimack and State ofNew Hampshire, have invented new and useful Improvements inDynamo-Electric Machines, of which the following is a specification.

My invention relates to dynamo-electric machines, and is particularlyadapted to variable speed, shunt wound, direct current motors, in whichthe speed of the armature may be -varied by varying the ampere turns inthe field magnets of the motor. Its object is to provide improved meansfor overcoming armature reaction and to secure sparkless commutation atthe brushes without the necessity. of shifting the brushes. This isaccomplished by the use, of commutating magnets in'conjunction with themain field mag- ,nets of the motor, the details of which will behereinafter pointed out.

In the. accompanying drawings which illustrate certainembodiments of myinvention:Figu re 1 shows a motor in, diagrammatic form containing oneform of my invention;, Fig. 2 shows a motor in diagrammatic formcontaining another form of my invention; Fig. 3 is an enlarged detailillustrating the main field magnet core and commutating magnet core withtheir respective v windings, of the form shown in Fig; 1; and

Fig. 4 is an enlarged detail illustrating the main field magnet core andcommutating magnet cores with their respective windings of the formshown in Fig. 2.

The frame of the field magnet comprises the yoke 1 provided with themain field magnet cores 2 projecting radially inward from the yoke. Eachmain core is preferably. provided with flaring or extended poleshoes,and the extended pole shoes are preferably made removable to admit ofplacing the coils upon the cores, or removing them therefrom, 45.

ready wound. In Figs. 1 and 3 isillustrated one form cit-removable poleshoe, which may be termed an L-shaped shoe comprising the tongue 3,fitted into a corresponding recess in the core, and the extended tip orshoe 4. In Figs. 2 and t is illustrated another form of removable poleshoe, which may be termed a T-shaped shoe, comprising the tongue 3,fitting into a corresponding recess in the core, and the pair ofoppositely extended tips or shoes 5 and 6. In either form a bolt- 7,

located back of the area of the field windings and in the magi'ieticyoke, holds the removable section in place. The frame is also providedwith commutating magnet cores projecting inward from the yoke l besidethe main cores 2. In the form shown in Figs. 1 and 3 one suchcommutating magnet core 8 is provided beside each main magnet core, andis separated therefrom by a space and extends from the yoke l to theouter side of the removable extended pole shoe 4.

In the form shown in Figs. 2 and 4 a pair of commutating magnet cores 9are provided, one on each side of each main core, and are separatedtherefrom by a space and extend from the yoke 1 to the outer side of theextensions 5 and 6 respectively of the removable pole shoe. Thus ineither case, both the main field magnetizing coils and the commutatingcoils may be made up and placed in or removed from position readywound,the extended pole shoes being removed for that purpose. The armature isshown at A, and the commutator at C.

The circuits are as follows: The commutating coils or windings 10 are inseries with each other and with the armature circuit as shown. The fieldcoils or windings 11 are in series with each other and in shunt with thearmature and the commutating magnet circuit. The field circuit is notshown as it is the same as is usual in such motors and will be readilyunderstood by those skilled in the art.

The field windings l1 inclose the main field core and also thecommutating cores and windings asshown in Figs. 3 and 4.

I claim: I

1. In a dynamo-electric machine, a frame for field and commutatingmagnets comprising a main core projecting from the yoke of the framehaving an extended pole shoe, and a commutating magnet core beside themain core .and projecting from said yoke to the outer side of saidextended pole shoe, a commutating winding on said commutating core inseries with the armature circuit, and a main field magnet winding inshunt with the armature circuit and inclosing both the main magnet coreand the commutating magnet core and winding.

2. In a dynamo-electric machine, a frame for field and commutatingmagnets comprising a main core projecting from the yoke of the frame,ha-vili a removable pole shoe extended in both dlrections, a pair ofcommutating magnet cores, one at each side of the main core, projectingfrom the yoke to the outer sides of the extensions of said pole shoe, :1commutating coil on each of said connnutating cores in series with eachother and with the armature circuit, and a main field coil in shunt withthe armature circuit 10 and inclosing both the main magnet core andconnnutating magnet cores and coils, said extensions of the removable,pole shoeadapted to hold in place the main field coil and thecommutating magnet coils.

Signed by me at Concord, New Hamp- 15-,

